Read The Universe Within Online
Authors: Neil Shubin
In 1787,
William Smith was hired to assess the financial value of the land within an estate in Somerset,
England. He was never to find monetary rewards; Smith’s gold was mined from something else altogether.
Smith set off to survey the rocks that lay exposed along streams, on hills, and inside
coal mines. Working in one of the pits of the older mines on the estate, he noticed that the rocks that border the mine were set in layers that he could easily recognize
by their colors and textures. On closer inspection, he discovered each layer was made of a particular kind of rock with a distinctive collection of fossils inside. Comparing these layers with others nearby, Smith had a rush of insight: the rock layers in the mine were similar to others at the surface elsewhere on the estate. As he looked closely at the layers, he saw he could use the fossils to match them in different regions, almost like a huge jigsaw puzzle.
Natural philosophers, even
Leonardo da Vinci, noted that it is possible to do this kind of comparison of rocks, fossils, and layers locally. Now, armed with this simple insight,
William Smith had the key to map the
geology of Earth: rocks and fossils arranged in layers.
Smith widened his hunt, first looking at the area around Bath,
then ultimately broadening his aspirations to cover all of Britain. This new task required money, and with neither an academic post nor the auspices of any scientific society Smith was strapped for cash. He convinced about one hundred patrons to fund his effort and set off to visit every rock exposure he could. He had expert help: his nephew
John Phillips had been his ward since the death of both of his parents, when Phillips was seven years old, and he accompanied his uncle on his excursions. By the age of fifteen Phillips had gained a phenomenal eye for fossils.
Today we use aerial photographs and GPS-driven survey equipment to construct geological maps, relying on comparing rocks fortuitously exposed at the surface and in deeper levels of bedrock brought up by
drill cores inside Earth. This is big science, often heavily financed by oil companies, mineral interests, and governments. Geological maps are the seed corn of research on Earth: everything we do on expedition starts here. In 1815, Smith accomplished this feat largely on his own using tools of his own design. When finished, the map was a triumph. Standing seven feet high, it revealed the relative position of major layers and fossil eras throughout Britain.
Unfortunately for Smith, however,
George Bellas Greenough was a leading light in the
London Geological Society at the time. Without Greenough’s support, Smith’s map could not gain the kind of professional traction needed to sell enough copies to pay his debts. Not only did Smith fail to get Greenough’s endorsement, but Greenough set off to produce his own map. And, piling the frustrations on his rival, Greenough made sure his map was cheaper than Smith’s.
Smith’s map was such a sales disaster that he ended up spending eleven weeks in debtors’ prison, returning to find his property seized. He had hoped to keep the fossil collection he made with his nephew but had to sell it to pay his debts. The situation went from bad to worse; about this time his wife went insane and had to be institutionalized.
Despite these setbacks, Smith’s legacies are many. He confirmed that the
fossils in rock layers change from the deepest ones, the oldest, to the highest and youngest ones. He revealed how fossils can be used as markers to trace the same layer across a wide area. And, importantly, he gave his nephew John Phillips an eye for fossils and geological layers.
If his uncle was an antiestablishment symbol troubled by an unfortunate marriage, then Phillips was the opposite: an established Oxford don who lived with his sister for all of his adult life. Phillips devoted himself to his uncle’s layers: his uncle recognized them, but Phillips was determined to find their meaning.
Work with his uncle gave Phillips the keen eye and fastidious technique that allowed him to assemble a prodigious and well-curated collection of shells, bones, and fossil impressions. Starting with his uncle’s map, he traced every known fossil from every layer and asked what happens at the transition between each layer.
Phillips saw three eras of time, each with its own world of fossils inside. The differences between these lost worlds were defined by a sharp boundary where creatures simply disappeared, only to be quickly replaced by new forms of life. Phillips saw these as three major divisions of geological time and named three
geological eras based on them:
Paleozoic,
Mesozoic, and
Cenozoic. He published his findings in 1855, and if you want to know how significant his work is, just go to any museum today. You will find his three great eras plastered on the time charts adjacent to the
dinosaurs, sharks, and trilobites.
This was an age of exploration of the natural world, and by looking at rocks and fossils, people began to formulate new ideas. Ships returned monthly from the far corners of the planet loaded with minerals, plants, animals, and rocks previously unknown to
science.
Natural philosophers of all stripes—people we would today call anatomists, paleontologists, and geologists—were in the center of the action, attempting to decipher the menagerie of biological curiosities that were being brought home.
One of the luminaries of this period, Georges Léopold Chrétien Frédéric Dagobert
Cuvier, had an ego as large as his name. Born to humble origins, he died Baron Cuvier, one of the leaders of the Natural History Museum in Paris.
One expedition returned to Paris from
South America with a giant six-foot-long skeleton shaped something like a small troop transport. With massive bones, large claws, and a skull with flattened teeth, this creature departed from anything in Cuvier’s experience until he looked closely at the vertebrae and limb bones. Being an astute anatomist, he saw that nestled inside this bizarre skeleton is the body plan of a sloth. But it was unlike any alive today.
Then several different kinds of elephant-like bones were brought to Cuvier’s attention. Seeing the differences from elephants, he identified the bones as reflecting a new species:
mammoths. But these discoveries, satisfying as they were for understanding the diversity of life, raised a troubling question: Where on Earth were these creatures still alive?
Cuvier made the connection: perhaps the large sloths and mammoths were no longer roaming the planet but instead revealed lost worlds of creatures. The concept of
extinction, something so fundamental to the way we see the world today and alien to many thinkers for millennia, now explained the goings-on inside the rocks.
One example after another of long-lost life appeared. Spelunkers in Germany ran across the large bones of a monster or dragon lying on a
cave floor. An anatomist from the local medical school saw that they were from some sort of bear, but one so large and oddly proportioned that it was unlike anything walking
Europe. Years later,
Thomas Jefferson found giant
mammoths, sloths, and other creatures near his home in Virginia.
Cuvier was a big thinker, and not satisfied with mere description, he drew generalizations from his observations, putting his theories on the line. To Cuvier, the conclusion was obvious: extinction was not only real but common. So prevalent and important was this concept that in an early monograph he declared, “All of these facts … seem to me to prove the existence of a world previous to ours, destroyed by some kind of
catastrophe.”
Cuvier’s idea, like that of
Phillips before him, was that catastrophes shaped Earth. This idea was the cutting-edge science of its day, having the weight of evidence and the stamp of eminent authority. It also was virtually ignored by scientists for over a hundred years.
The notion of catastrophes lay in direct conflict with the reigning scientific approach of the day. This alternate notion was so powerful in explaining Earth that it did not allow interlopers. Its success was derived from the motto “Use the present to infer the past.” This idea is so simple and elegant that we take it completely for granted. If you see a car parked on one side of the street on Monday but by Thursday it is on the opposite side, you infer that somebody drove it and later parked it in the new place. It would be a far stretch to imagine that the car flew by its own volition or was carried by a special wind. The mechanisms at work today explain yesterday; no magic or extraordinary physics need to be involved.
The same kind of reasoning applies to the history of rocks, cliffs, and layers. The major forces at work around us today are wind, rain, and
gravity—all products of the laws of physics and chemistry. If they shape today’s world, they must have acted in the past to make the rock record. The
Grand Canyon clearly is a deep cut in the ground with the Colorado River at its base.
The known earthly cause for the formation of the canyon is the erosive action of water cutting the rock and the relative uplift of rocks around it. But these mechanisms are very slow. Sand doesn’t compact into rock layers overnight any more than a flowing river carves a canyon thousands of feet deep in a day, or even a year. The implication for the formation of the Grand Canyon, or any geological feature, is that it took millions of years to come about.
This gradual approach provided an explanation for the formation of canyons, coral reefs, and coastlines: not only were present-day mechanisms capable of explaining Earth’s history; they implied that most changes to species or the planet would be slow. Looking at Earth today, nobody could imagine, much less see, a mechanism that could bring about a global cataclysm to life on Earth.
Theories of catastrophes, like those proposed by
Phillips and
Cuvier, became decidedly oddball views, relegated to a kind of lunatic fringe of scientific thought. Phillips continued to work, but by the time of his passing in 1874, from a fall down the steps of All Souls College at Oxford, the notion of catastrophes was already dead—killed by the reigning dogma of gradual change.
The town of Stafford is nestled in south-central Kansas; its population consists of about a thousand households, with a high school so small they play eight-man football. In the early twentieth century, the Newells were known to locals as the go- to people for knowledge about local natural history. When farmers hit a strange rock, the patriarch of the Newell family saw it for what it really was, a
mammoth tooth. Six-year-old
Norman Newell observed these encounters, and they changed the way he thought about home: the flatlands that are Kansas today were once grasslands
and forests that housed large
mammals. Norman’s interest in paleontology grew, and he excelled to the point that he won a spot in the prestigious graduate program in paleontology at
Yale University, which by this time, the 1930s, had become one of the major centers of research in the field.
Norman Newell’s work at Yale was a family affair; his wife supported him financially, cataloging specimens for Yale’s Peabody Museum, until Newell was able to obtain a scholarship in his second year in the program. He set off studying clams, mollusks, and other animals with two
shells separated by a hinge. Newell was quick to see the advantages of studying these animals. With hard shells, they readily fossilize and are very common throughout the ancient layers of the world. Newell did something few others at the time even considered important: he used living
shelled animals to infer the behavior of extinct ones.